Oxide thin films have been widely used in semiconductor industries and optoelectronic industries. Generally, oxide thin films are manufactured through gas-phase method and liquid-phase method.
Gas-phase method, i.e. evaporation method and sputtering method, is implemented in a vacuum chamber with an expensive device. Prior to manufacturing the oxide thin film, vacuuming the chamber is crucial and necessary. However, vacuuming the vacuum chamber is time-consuming and the vacuum chamber limits area for the oxide thin film to grow.
Liquid-phase method, i.e. sol-gel method and aqueous solution method, is complicated, time-consuming and disadvantageous to control morphology and characteristic of the oxide thin film while being implemented. For instance, a tungsten oxide thin film through aqueous solution method is prepared by following steps. Tungsten powder and hydrogen peroxide are blended for 6 hours. After removing the excessive hydrogen peroxide, a first solution is obtained. Acetate and the first solution are blended and refluxed for 12 hours and a second solution is obtained. Then a vacuuming process is implemented to the second solution, a surfactant is blended with the second solution for 1 hour and a third solution is obtained. The third solution is then placed on a spinning device to use a centrifugal force to separate the third solution, and a settled solution is obtained. Finally, the settled solution is coated on a substrate and heated to form a tungsten oxide thin film on the substrate. However, the oxide thin film is un-reproducible because process parameters are not easy to be controlled in liquid-phase method. That is, if the process parameters, i.e. blending time and depositing time of the foregoing solutions, are slightly varied, an oxide thin film of different morphology and characteristic is manufactured.